Art of preserving wood.



OLIVER. P. M. Goss, or sEArTLmwAsHINGroN.

ART oF PRESRVING woon.

Specification of Letters Patent.

Application filed November 9, 1916. SeriaNo. 130,461.

i To all 'whom t may concern.'

Be it known that I, OLIVER P. i Goss,

'i a citizen of the United States, and a resident of Seattle, King county, State of Washington, have invented a certain new and useful Improvement in the Art of Preserving Wood, of which the following is a specification.

In the preservative treatmentof timber two methods are generally employed, namely, the timber may be immersed in the preserving fluid' lin an-open tank, or"

under pressure; the latter being the method more generally used, since some timber, notably Douglas fir, lresists the penetration of the preserving fluid to too great a degree yacross the grain, in an open tank, for such treatment to be practicable.v The pressure method is, however, wasteful and unreliable, in fact deceptive, because whilera given quantity of the preserving Huid may be. driven into the pores of the timber, it' is ,found that the larger portion of the liuid wastefully collects in certain areas while other areas are left practically Without any. For this reason it is preferred to use the so-called perforation method, which consists in putting a number of holes into the outer surfaceof the wood and causing the preservative to enter the pores through such holes'. .In this way there is assured a definite degree of penetration, and a wider distribution of the preservative. But the latter method was also inelicient, for the holes or perforations above referred to were put into the timber more'or less at random, that is, without regard to thenormal, minimum spread of the preservative and the`result was certain parts of the timber received an excess of the preservative while other parts receive an insuiiicient treatment. Another objection to said haphazard system of perforating the timber lies in the fact that it frequently results in the putting of a great' number of perforations in one plane of cross section of the timber, and hence the transversestrength of the timber at that plane of cross section is materially reduced.

With the object of overcoming the above objections, and also for the purpose of providing a very simple and economical way of treating timber with a preservative fluid,

to any desired degree of impregnation, and also insuring a substantially uniform impregnation of the surface treated by means of a minimum perforation of the timber,

I have invented the following method: The outer surface is perforated to a desired depth by holes systematically located at relative distances apart, botl'i transversely and longitudinally, that is, with .the grain of the wood and crosswise thereof, as predetermined by the known normal spread, that is,

' Patented aan. afieis.

absorption, of the preservative with and across the grain of the wood under given factors of time of immersion, pressure applied and size of perforations. The result of such procedure is a substantially uniform treatment of the timber to a depth equal to that of the perforations, and without waste of the preservative.

In order to prevent a decrease in the transverse strength of the timber by the perforations put into the wood, I arrange the perforations in a series of planes lying diagof nally with the grainof the Wood. This, together with the other above mentioned features of my invention, can better be understood by having reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic, sectional view of a block of timber representing a portion thereof as partially treated by my improved taken parallel with the bore of the perfora tions.

a represents a block of timber; b is'the grain in same; c are the perforations through which a preservative fluid, such, for example, as creosote oil, is introduced into the timber; and d represents diagrammatically the areas over which the preserva- 'tive spreads from each hole.

As is commonly known, the extent of absorption of a fluid will be much f greater along the grain of the wood than across the same. The normal, minimum extent of the absorption, both with and across the grain of any given kind of timber, isfreadily determined .by experiment for any particular length of time of immersion of the material in the preservative, pressure applied, and size of the perforations, and thesamev is then toibe noted, and later, in practisingmy art, the perforations are to be made spaced apart accordingly. Furthermore, these periie forations are to` be relatively so located that the margins of the previously ascertained, and therefore known, minimum areas impregnated from the perforations will overlap at their margins.

timber in the process of being treated, but.

the adjacent treated areas have not yet come together and overlapped, as will be the case when the preservative has been fully absorbed by the timber.

I have tried out my invention in connection with both of the 'above named two general methods of treatment, andv obtained these results:

. By open tank method, in treating air-seasoned Douglas fir, previously perforated by small holes one-sixteenth of an inch in diameter and spaced four inches apart along the grain, and one-eighth inch apart across the grain, I obtained complete and substantially uniform penetration. lThe method of procedure resulting in this complete enetration, to the full depth of the per oration, was asfollmys: The timber was placed in the open tank and the preservative oil Was introduced.

The heat was then discontinued and the material allowed to cool down in the oil, which required ya period of approximately twelve hours, after which the timber may ,b'e removed and is ready for use.

My vsecond test was made under`r the pressure method. Complete penetration was se# cured the full depth of the perforations, the procedure being as follows: Air-seasoned 7 The timber was bolled 1n the` `oil for four .hours at 215 deg. Fahrenheit.

lDouglas fir specimens Were perforated to a `depth of three-fourths ofan inch by a tool one-eighth inch in Width acrossthe grain. The spacing of the holes from each other along the grain was seven inches, and the spacing across the grain was three-eighths of an inch. `The timbers perforated as herein described were yplaced in a pressure retort, and preservative oil was Iintroduced and gaised to a temperature of 170 degrees Fahrenheit. The material was subjected to this temperature for` four hours, after which pressure Was applied to the oil, varying from 0 to 120 pounds per square inch. About one hour Was required to raise the pressure to 120 pounds. And it was held at this pressure for a period of two hours. During the pressure the temperature of the oil Was 170 degrees Fahrenheit.

After such treatment the timber is ready for use. Y

I claim:

1. The method of preparing a piece of wood for impregnation which comprises placing in a surface of the piece equally spaced rows of equally spaced holes so arranged that the distances between adjacent holes are proportional to the rates of spread of the impregnating fluid in the directions in which the distances are measured.

2. The method of preparing a piece of wood for impregnation which comprises placing in a surface of the piece equally spaced rows of equally spaced holes, so arranged that no roW of holes extends in a di`v rection directly across the grain of the piece, and arranged so that the distances between adjacent holes are proportional to the rates of spread of the impregnating fluid in the directions in which the distances are measure 70. PfM. GOSS. 

